[转]java 从数据库表反射出实体类，自动生成实体类

本文转自：http://blog.csdn.net/goodleiwei/article/details/8439023

01.package com.db.gen.entity.tool;  
02.  
03.  
04.import java.io.File;  
05.import java.io.FileWriter;  
06.import java.io.IOException;  
07.import java.io.PrintWriter;  
08.import java.sql.Connection;  
09.import java.sql.DriverManager;  
10.import java.sql.PreparedStatement;  
11.import java.sql.ResultSetMetaData;  
12.import java.sql.SQLException;  
13.import java.util.Date;  
14.  
15.public class GenEntityMysql {  
16.      
17.    private String packageOutPath = "com.user.entity";//指定实体生成所在包的路径  
18.    private String authorName = "封狼居胥";//作者名字  
19.    private String tablename = "user";//表名  
20.    private String[] colnames; // 列名数组  
21.    private String[] colTypes; //列名类型数组  
22.    private int[] colSizes; //列名大小数组  
23.    private boolean f_util = false; // 是否需要导入包java.util.*  
24.    private boolean f_sql = false; // 是否需要导入包java.sql.*  
25.      
26.    //数据库连接  
27.    private static final String URL ="jdbc:mysql://localhost:3306/jbpm";  
28.    private static final String NAME = "root";  
29.    private static final String PASS = "root";  
30.    private static final String DRIVER ="com.mysql.jdbc.Driver";  
31.  
32.    /* 
33.     * 构造函数 
34.     */  
35.    public GenEntityMysql(){  
36.        //创建连接  
37.        Connection con;  
38.        //查要生成实体类的表  
39.        String sql = "select * from " + tablename;  
40.        PreparedStatement pStemt = null;  
41.        try {  
42.            try {  
43.                Class.forName(DRIVER);  
44.            } catch (ClassNotFoundException e1) {  
45.                // TODO Auto-generated catch block  
46.                e1.printStackTrace();  
47.            }  
48.            con = DriverManager.getConnection(URL,NAME,PASS);  
49.            pStemt = con.prepareStatement(sql);  
50.            ResultSetMetaData rsmd = pStemt.getMetaData();  
51.            int size = rsmd.getColumnCount();   //统计列  
52.            colnames = new String[size];  
53.            colTypes = new String[size];  
54.            colSizes = new int[size];  
55.            for (int i = 0; i < size; i++) {  
56.                colnames[i] = rsmd.getColumnName(i + 1);  
57.                colTypes[i] = rsmd.getColumnTypeName(i + 1);  
58.                  
59.                if(colTypes[i].equalsIgnoreCase("datetime")){  
60.                    f_util = true;  
61.                }  
62.                if(colTypes[i].equalsIgnoreCase("image") || colTypes[i].equalsIgnoreCase("text")){  
63.                    f_sql = true;  
64.                }  
65.                colSizes[i] = rsmd.getColumnDisplaySize(i + 1);  
66.            }  
67.              
68.            String content = parse(colnames,colTypes,colSizes);  
69.              
70.            try {  
71.                File directory = new File("");  
72.                //System.out.println("绝对路径："+directory.getAbsolutePath());  
73.                //System.out.println("相对路径："+directory.getCanonicalPath());  
74.                String path=this.getClass().getResource("").getPath();  
75.                  
76.                System.out.println(path);  
77.                System.out.println("src/?/"+path.substring(path.lastIndexOf("/com/", path.length())) );  
78.//              String outputPath = directory.getAbsolutePath()+ "/src/"+path.substring(path.lastIndexOf("/com/", path.length()), path.length()) + initcap(tablename) + ".java";  
79.                String outputPath = directory.getAbsolutePath()+ "/src/"+this.packageOutPath.replace(".", "/")+"/"+initcap(tablename) + ".java";  
80.                FileWriter fw = new FileWriter(outputPath);  
81.                PrintWriter pw = new PrintWriter(fw);  
82.                pw.println(content);  
83.                pw.flush();  
84.                pw.close();  
85.            } catch (IOException e) {  
86.                e.printStackTrace();  
87.            }  
88.              
89.        } catch (SQLException e) {  
90.            e.printStackTrace();  
91.        } finally{  
92.//          try {  
93.//              con.close();  
94.//          } catch (SQLException e) {  
95.//              // TODO Auto-generated catch block  
96.//              e.printStackTrace();  
97.//          }  
98.        }  
99.    }  
100.  
101.    /** 
102.     * 功能：生成实体类主体代码 
103.     * @param colnames 
104.     * @param colTypes 
105.     * @param colSizes 
106.     * @return 
107.     */  
108.    private String parse(String[] colnames, String[] colTypes, int[] colSizes) {  
109.        StringBuffer sb = new StringBuffer();  
110.          
111.        //判断是否导入工具包  
112.        if(f_util){  
113.            sb.append("import java.util.Date;\r\n");  
114.        }  
115.        if(f_sql){  
116.            sb.append("import java.sql.*;\r\n");  
117.        }  
118.        sb.append("package " + this.packageOutPath + ";\r\n");  
119.        sb.append("\r\n");  
120.        //注释部分  
121.        sb.append("   /**\r\n");  
122.        sb.append("    * "+tablename+" 实体类\r\n");  
123.        sb.append("    * "+new Date()+" "+this.authorName+"\r\n");  
124.        sb.append("    */ \r\n");  
125.        //实体部分  
126.        sb.append("\r\n\r\npublic class " + initcap(tablename) + "{\r\n");  
127.        processAllAttrs(sb);//属性  
128.        processAllMethod(sb);//get set方法  
129.        sb.append("}\r\n");  
130.          
131.        //System.out.println(sb.toString());  
132.        return sb.toString();  
133.    }  
134.      
135.    /** 
136.     * 功能：生成所有属性 
137.     * @param sb 
138.     */  
139.    private void processAllAttrs(StringBuffer sb) {  
140.          
141.        for (int i = 0; i < colnames.length; i++) {  
142.            sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + ";\r\n");  
143.        }  
144.          
145.    }  
146.  
147.    /** 
148.     * 功能：生成所有方法 
149.     * @param sb 
150.     */  
151.    private void processAllMethod(StringBuffer sb) {  
152.          
153.        for (int i = 0; i < colnames.length; i++) {  
154.            sb.append("\tpublic void set" + initcap(colnames[i]) + "(" + sqlType2JavaType(colTypes[i]) + " " +   
155.                    colnames[i] + "){\r\n");  
156.            sb.append("\tthis." + colnames[i] + "=" + colnames[i] + ";\r\n");  
157.            sb.append("\t}\r\n");  
158.            sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n");  
159.            sb.append("\t\treturn " + colnames[i] + ";\r\n");  
160.            sb.append("\t}\r\n");  
161.        }  
162.          
163.    }  
164.      
165.    /** 
166.     * 功能：将输入字符串的首字母改成大写 
167.     * @param str 
168.     * @return 
169.     */  
170.    private String initcap(String str) {  
171.          
172.        char[] ch = str.toCharArray();  
173.        if(ch[0] >= 'a' && ch[0] <= 'z'){  
174.            ch[0] = (char)(ch[0] - 32);  
175.        }  
176.          
177.        return new String(ch);  
178.    }  
179.  
180.    /** 
181.     * 功能：获得列的数据类型 
182.     * @param sqlType 
183.     * @return 
184.     */  
185.    private String sqlType2JavaType(String sqlType) {  
186.          
187.        if(sqlType.equalsIgnoreCase("bit")){  
188.            return "boolean";  
189.        }else if(sqlType.equalsIgnoreCase("tinyint")){  
190.            return "byte";  
191.        }else if(sqlType.equalsIgnoreCase("smallint")){  
192.            return "short";  
193.        }else if(sqlType.equalsIgnoreCase("int")){  
194.            return "int";  
195.        }else if(sqlType.equalsIgnoreCase("bigint")){  
196.            return "long";  
197.        }else if(sqlType.equalsIgnoreCase("float")){  
198.            return "float";  
199.        }else if(sqlType.equalsIgnoreCase("decimal") || sqlType.equalsIgnoreCase("numeric")   
200.                || sqlType.equalsIgnoreCase("real") || sqlType.equalsIgnoreCase("money")   
201.                || sqlType.equalsIgnoreCase("smallmoney")){  
202.            return "double";  
203.        }else if(sqlType.equalsIgnoreCase("varchar") || sqlType.equalsIgnoreCase("char")   
204.                || sqlType.equalsIgnoreCase("nvarchar") || sqlType.equalsIgnoreCase("nchar")   
205.                || sqlType.equalsIgnoreCase("text")){  
206.            return "String";  
207.        }else if(sqlType.equalsIgnoreCase("datetime")){  
208.            return "Date";  
209.        }else if(sqlType.equalsIgnoreCase("image")){  
210.            return "Blod";  
211.        }  
212.          
213.        return null;  
214.    }  
215.      
216.    /** 
217.     * 出口 
218.     * TODO 
219.     * @param args 
220.     */  
221.    public static void main(String[] args) {  
222.          
223.        new GenEntityMysql();  
224.          
225.    }  
226.  
227.}  

01.package com.db.gen.entity.tool;  
02.  
03.  
04.import java.io.File;  
05.import java.io.FileWriter;  
06.import java.io.IOException;  
07.import java.io.PrintWriter;  
08.import java.sql.Connection;  
09.import java.sql.DriverManager;  
10.import java.sql.PreparedStatement;  
11.import java.sql.ResultSet;  
12.import java.sql.ResultSetMetaData;  
13.import java.sql.SQLException;  
14.import java.sql.Statement;  
15.import java.util.Date;  
16.  
17.public class GenEntityOracle {  
18.      
19.    private String packageOutPath = "com.user.entity";//指定实体生成所在包的路径  
20.    private String authorName = "封狼居胥";//作者名字  
21.    private String tablename = "emp";//表名  
22.    private String[] colnames; // 列名数组  
23.    private String[] colTypes; //列名类型数组  
24.    private int[] colSizes; //列名大小数组  
25.    private boolean f_util = false; // 是否需要导入包java.util.*  
26.    private boolean f_sql = false; // 是否需要导入包java.sql.*  
27.      
28.    //数据库连接  
29.     private static final String URL ="jdbc:oracle:thin:@127.0.0.1:1521:ORCL";  
30.     private static final String NAME = "scrot";  
31.     private static final String PASS = "tiger";  
32.     private static final String DRIVER ="oracle.jdbc.driver.OracleDriver";  
33.  
34.    /* 
35.     * 构造函数 
36.     */  
37.    public GenEntityOracle(){  
38.        //创建连接  
39.        Connection con;  
40.        //查要生成实体类的表  
41.        String sql = "select * from " + tablename;  
42.        Statement pStemt = null;  
43.        try {  
44.            try {  
45.                Class.forName(DRIVER);  
46.            } catch (ClassNotFoundException e1) {  
47.                // TODO Auto-generated catch block  
48.                e1.printStackTrace();  
49.            }  
50.            con = DriverManager.getConnection(URL,NAME,PASS);  
51.            pStemt = (Statement) con.createStatement();  
52.            ResultSet rs = pStemt.executeQuery(sql);  
53.            ResultSetMetaData rsmd = rs.getMetaData();  
54.            int size = rsmd.getColumnCount();   //统计列  
55.            colnames = new String[size];  
56.            colTypes = new String[size];  
57.            colSizes = new int[size];  
58.            for (int i = 0; i < size; i++) {  
59.                colnames[i] = rsmd.getColumnName(i + 1);  
60.                colTypes[i] = rsmd.getColumnTypeName(i + 1);  
61.                  
62.                if(colTypes[i].equalsIgnoreCase("date") || colTypes[i].equalsIgnoreCase("timestamp")){  
63.                    f_util = true;  
64.                }  
65.                if(colTypes[i].equalsIgnoreCase("blob") || colTypes[i].equalsIgnoreCase("char")){  
66.                    f_sql = true;  
67.                }  
68.                colSizes[i] = rsmd.getColumnDisplaySize(i + 1);  
69.            }  
70.              
71.            String content = parse(colnames,colTypes,colSizes);  
72.              
73.            try {  
74.                File directory = new File("");  
75.                //System.out.println("绝对路径："+directory.getAbsolutePath());  
76.                //System.out.println("相对路径："+directory.getCanonicalPath());  
77.                String path=this.getClass().getResource("").getPath();  
78.                  
79.                System.out.println(path);  
80.                System.out.println("src/?/"+path.substring(path.lastIndexOf("/com/", path.length())) );  
81.//              String outputPath = directory.getAbsolutePath()+ "/src/"+path.substring(path.lastIndexOf("/com/", path.length()), path.length()) + initcap(tablename) + ".java";  
82.                String outputPath = directory.getAbsolutePath()+ "/src/"+this.packageOutPath.replace(".", "/")+"/"+initcap(tablename) + ".java";  
83.                FileWriter fw = new FileWriter(outputPath);  
84.                PrintWriter pw = new PrintWriter(fw);  
85.                pw.println(content);  
86.                pw.flush();  
87.                pw.close();  
88.            } catch (IOException e) {  
89.                e.printStackTrace();  
90.            }  
91.              
92.        } catch (SQLException e) {  
93.            e.printStackTrace();  
94.        } finally{  
95.//          try {  
96.//              con.close();  
97.//          } catch (SQLException e) {  
98.//              // TODO Auto-generated catch block  
99.//              e.printStackTrace();  
100.//          }  
101.        }  
102.    }  
103.  
104.    /** 
105.     * 功能：生成实体类主体代码 
106.     * @param colnames 
107.     * @param colTypes 
108.     * @param colSizes 
109.     * @return 
110.     */  
111.    private String parse(String[] colnames, String[] colTypes, int[] colSizes) {  
112.        StringBuffer sb = new StringBuffer();  
113.          
114.        //判断是否导入工具包  
115.        if(f_util){  
116.            sb.append("import java.util.Date;\r\n");  
117.        }  
118.        if(f_sql){  
119.            sb.append("import java.sql.*;\r\n");  
120.        }  
121.        sb.append("package " + this.packageOutPath + ";\r\n");  
122.        sb.append("\r\n");  
123.        //注释部分  
124.        sb.append("   /**\r\n");  
125.        sb.append("    * "+tablename+" 实体类\r\n");  
126.        sb.append("    * "+new Date()+" "+this.authorName+"\r\n");  
127.        sb.append("    */ \r\n");  
128.        //实体部分  
129.        sb.append("\r\n\r\npublic class " + initcap(tablename) + "{\r\n");  
130.        processAllAttrs(sb);//属性  
131.        processAllMethod(sb);//get set方法  
132.        sb.append("}\r\n");  
133.          
134.        //System.out.println(sb.toString());  
135.        return sb.toString();  
136.    }  
137.      
138.    /** 
139.     * 功能：生成所有属性 
140.     * @param sb 
141.     */  
142.    private void processAllAttrs(StringBuffer sb) {  
143.          
144.        for (int i = 0; i < colnames.length; i++) {  
145.            sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + ";\r\n");  
146.        }  
147.          
148.    }  
149.  
150.    /** 
151.     * 功能：生成所有方法 
152.     * @param sb 
153.     */  
154.    private void processAllMethod(StringBuffer sb) {  
155.          
156.        for (int i = 0; i < colnames.length; i++) {  
157.            sb.append("\tpublic void set" + initcap(colnames[i]) + "(" + sqlType2JavaType(colTypes[i]) + " " +   
158.                    colnames[i] + "){\r\n");  
159.            sb.append("\tthis." + colnames[i] + "=" + colnames[i] + ";\r\n");  
160.            sb.append("\t}\r\n");  
161.            sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n");  
162.            sb.append("\t\treturn " + colnames[i] + ";\r\n");  
163.            sb.append("\t}\r\n");  
164.        }  
165.          
166.    }  
167.      
168.    /** 
169.     * 功能：将输入字符串的首字母改成大写 
170.     * @param str 
171.     * @return 
172.     */  
173.    private String initcap(String str) {  
174.          
175.        char[] ch = str.toCharArray();  
176.        if(ch[0] >= 'a' && ch[0] <= 'z'){  
177.            ch[0] = (char)(ch[0] - 32);  
178.        }  
179.          
180.        return new String(ch);  
181.    }  
182.  
183.    /** 
184.     * 功能：获得列的数据类型 
185.     * @param sqlType 
186.     * @return 
187.     */  
188.    private String sqlType2JavaType(String sqlType) {  
189.          
190.        if(sqlType.equalsIgnoreCase("binary_double")){  
191.            return "double";  
192.        }else if(sqlType.equalsIgnoreCase("binary_float")){  
193.            return "float";  
194.        }else if(sqlType.equalsIgnoreCase("blob")){  
195.            return "byte[]";  
196.        }else if(sqlType.equalsIgnoreCase("blob")){  
197.            return "byte[]";  
198.        }else if(sqlType.equalsIgnoreCase("char") || sqlType.equalsIgnoreCase("nvarchar2")   
199.                || sqlType.equalsIgnoreCase("varchar2")){  
200.            return "String";  
201.        }else if(sqlType.equalsIgnoreCase("date") || sqlType.equalsIgnoreCase("timestamp")  
202.                 || sqlType.equalsIgnoreCase("timestamp with local time zone")   
203.                 || sqlType.equalsIgnoreCase("timestamp with time zone")){  
204.            return "Date";  
205.        }else if(sqlType.equalsIgnoreCase("number")){  
206.            return "Long";  
207.        }  
208.          
209.        return "String";  
210.    }  
211.      
212.    /** 
213.     * 出口 
214.     * TODO 
215.     * @param args 
216.     */  
217.    public static void main(String[] args) {  
218.          
219.        new GenEntityOracle();  
220.          
221.    }  
222.  
223.}  


 

通过改造可以实现mysql和oracle的了

参考地址：http://www.oschina.net/code/snippet_857839_15477